Endoscopic accessory attachment mechanism

ABSTRACT

The present invention provides a mechanism for attaching accessory devices to the distal end of an endoscope or catheter. The engagement mechanism comprises a bracing member ( 392 ) that engages a surface of the endoscope ( 20 ) and a ramp surface ( 360 ), which applies a gripping force to an opposing surface of the endoscope, preferably through a wedge member ( 372 ). The bracing member ( 392 ) may comprise an elongate element that extends partially into the working channel of the endoscope or may comprise an element that engages a portion of the total circumference of the outside surface of the endoscope. The ramp surface ( 360 ) is inclined at an acute angle from the longitudinal axis of the endoscope and preferably engages with a slidable wedge in a cooperative arrangement that serves to reduce the distance between the wedge ( 372 ) and the bracing member ( 392 ) as the wedge slides on the ramp to engage a portion of the endoscope therebetween.

This application claims the benefit of Provisional Application No.60/204,155, filed May 15, 2000.

FIELD OF THE INVENTION

The present invention relates to mechanisms and methods for attaching anendoscopic accessory component to a distal end of an endoscope.

BACKGROUND OF THE INVENTION

Endoscopic procedures provide a desirable, minimally invasivealternative to surgery in treating various internal ailments of thehuman body. Endoscopes comprise a long cylindrical tube having severalchannels or lumens, and can be inserted through a natural body lumen toan internal treatment site. Various procedures can be conducted bynavigating instruments through the working channels of the endoscope.Frequently, viewing capability is provided through one of the channelsof the endoscope to aid in conducting the procedure. Attachment ofvarious accessory tools to the distal end of the endoscope that areremotely operable through a working channel of the endoscope and/orelements that track along the outside of the endoscope to the treatmentsite can broaden the range of procedures viable for endoscopictechniques. Accessory attachments for endoscopes are currently availableto perform band ligation, mucosectomy and for endoscopic suturing andsuture knot advancement. Such accessory devices must be securelyattached to the distal end of the endoscope to prevent accidentalrelease of the accessory in the patient potentially causing seriouscomplications.

Presently available means for attaching such accessories to the distalend of an endoscope utilize a friction fit or set screws that arecumbersome for a physician to operate. Friction fit endoscopicattachment mechanisms comprise a cylindrical ring at the proximal end ofthe accessory device sized to fit tightly around the distal end of theendoscope. The close sizing and proper material selection providefrictional contact to hold the accessory onto the distal end of theendoscope. However, the close fitting high frictional engagementprovided by the cylindrical attachment mechanism make loading theaccessory onto the distal end of the endoscope cumbersome and timeconsuming. Additionally, the closely sized cylindrical component matchesonly one endoscope size and, therefore, different sizes of attachmentmechanisms must be produced and kept on hand if different sizedendoscopes are expected to be used.

Another type of attachment mechanism uses set screws threaded through anendoscopic accessory which push a movable shoe into tight engagementwith the outside surface of the endoscope while another portion of theaccessory device extends partially into the working channel of theendoscope to provide leverage against advancement of the set screw. Suchan attachment mechanism has been used to secure an endoscopic suturingcapsule as disclosed in U.S. Pat. Nos. 4,841,888, 5,037,021, 5,080,663,5,792,153, all of which are incorporated herein by reference in theirentirety. Although the movable shoe secured by the set screws provides asecure engagement for a range of endoscope sizes, it is cumbersome andtime consuming for the physician to tighten the set screws to secure thedevice prior to the procedure.

It would be desirable to provide an endoscopic accessory attachmentmechanism that securely attaches the accessory to the distal end of anendoscope and that can be applied easily and rapidly. It is an object ofthe present invention to provide such a mechanism and associated methodsfor its use.

It is noted that in the description of the present invention, “distal”refers to the direction along the device pathway leading internally tothe patient and “proximal refers to the direction leading externallyfrom the patient.

SUMMARY OF THE INVENTION

The present invention provides an endoscopic accessory attachmentmechanism that utilizes a bracing member, a ramp surface and,preferably, a wedge slidable on the ramp surface to apply a compressiveengagement force on surfaces of the distal end of an endoscope to securethe accessory. The engagement force is created by compression of thedistal end of the endoscope between the bracing member and the ramp andwedge elements. The ramp's surface permits the compressive force appliedto the endoscope to be adjustable so that the accessory can be appliedto the distal end of the endoscope easily, then tightened. The additionof the wedge element, slidable on the ramp surface enhances theadjustability of the compressive engagement force, provides a secureengagement pad by it s top surface to contact the exterior of theendoscope and may provide a self-locking feature depending on theorientation of the ramp surface. The ramp surface also permitsvariability in the outside diameter of the endoscope to which the deviceis secured.

The attachment mechanism may be incorporated as part of the endoscopicaccessory configured to be utilized at the distal end of the endoscope.Alternatively, the mechanism may be assembled to the accessory in asecondary operation such as adhesive bonding or riveting. Also themechanism may be separate, but releasably engageable with the accessory.The mechanism may be configured as a coupling, configured as describedherein to engage the endoscope at one end with the other end engaged asnecessary to connect to an existing endoscopic accessory device. Themechanism does not interfere with the use of the channels and featuresof the endoscope and does not damage the surfaces of the endoscope byits attachment. The attachment mechanism can accommodate a range ofcommonly used endoscope diameter sizes, for example, such as scopediameters between 9.2 to 9.8 mm, providing the same secure engagementwith each. However it is noted that the securement device of the presentinvention is equally applicable to and can be configured to correspondto endoscopes of larger or smaller sizes or catheters. To accommodateendoscopes that are significantly smaller or larger than the most commonsizes, or to accommodate catheters, which are typically smaller and moreflexible than endoscopes, the securement system can be madecorrespondingly larger or smaller to match the scale of the device inquestion.

The bracing member should be configured to lie in a plane that isparallel to the longitudinal axis of the endoscope as determined whenthe accessory is in the intended, attached position on the endoscope.The bracing member should be configured to engage a surface of theendoscope such as the outside surface of the scope or an internalsurface such as the lumen wall of the working channel. In the case ofengagement with the working channel, the bracing member may comprise atube slidable within a small portion of the working channel. To engagethe outer surface of the endoscope, the bracing member may be configuredas a cylinder to encircle the entire circumference of the distal end ofthe endoscope or may take a form of a partial cylinder to engage only afractional arc length of the circumference of the distal end of theendoscope.

The ramp surface is configured to project proximally past the distalface of the endoscope when the accessory is fully engaged with theendoscope. The ramp surface is inclined at an acute angle to thelongitudinal axes of the endoscope and the bracing member. A forwardfacing ramp is defined when the angle of the ramp defines a rise thatincreases as the ramp projects proximally. With a forward facing ramp,an engagement force with the endoscope may be created as the accessoryis slid proximally onto the distal end of the endoscope. With the properspacing between the fixed bracing member and ramp surface, surfaces ofthe endoscope can be compressed between the ramp surface and bracingmember as a force is applied to move the accessory relative to theendoscope in a proximal direction.

In a preferred embodiment, a wedge, slidable on the ramp surface is alsoprovided with the mechanism to translate the engagement force from theramp to a surface of the endoscope. A wedge facilitates application ofthe device to the endoscope, accommodates a varied range of endoscopesizes and may provide a self-locking feature, depending on theorientation of the ramp surface. The wedge, preferably, includes a topsurface that serves as an engagement pad for contacting a surface of theendoscope. The bottom surface of the wedge is preferably inclined at anacute angle corresponding to the angle between the ramp surface andlongitudinal axis of the endoscope. Therefore, as the bottom surface ofthe wedge slides in mated contact with the ramp surface, the top surfaceof the wedge will be parallel to the longitudinal axis of the endoscopeand thus to the outside surface of the endoscope to facilitate secureengagement.

Using a wedge in combination with the ramp surface, the ramp may beoriented to be forward (as defined above) or reverse, such that theangle defines a rise that decreases in the proximal direction. Thebottom surface of the wedge may have projecting guides that slide inkeyways formed in the ramp surface to keep the wedge aligned as itslides on the ramp. Additionally, the wedge may be biased to one end ofthe ramp surface by a biasing member, such as one or more small coilsprings. Biasing the wedge to its maximum range of travel on the highestpart of the ramp helps to provide a self-locking feature for the systemin that the wedge is maintained at the highest possible position on theramp to provide the greatest compressive force on the surface of theendoscope at all times.

In use, a mechanism having a reverse ramp and biasing means to maintainthe wedge at the proximal end (highest point) of the ramp would beapplied as follows. The accessory is engaged with the distal end of theendoscope, being slid proximally so that the bracing member engages theintended surface of the endoscope and the top surface of the wedgeengages the outside surface of the endoscope. As the device is pushedproximally, the wedge slides down the ramp slightly to permit acceptanceof the device onto the distal end of the endoscope. Additionally thewedge may have a beveled edge to aid in engaging and sliding under theadvancing endoscope. Once the device is sufficiently advanced onto theendoscope, the wedge will be biased to the highest possible point on theramp by a biasing means. A backstop at the distal end of the ramp thatremains distal to the distal end of the endoscope indicates to the userthe extent to which the device has been loaded onto the endoscope. Flushengagement between the distal face of the endoscope and backstop is notnecessarily required for secure mounting.

A separate leverage tool may be provided so that the user can engage thewedge directly to apply an additional longitudinal force to drive thewedge further up the ramp, increasing the compressive force on thesurfaces of the endoscope, now locked between the bracing member and thewedge. Not only is secure engagement achieved initially, but any forceacting to move the accessory distally relative to the endoscope (aremoval direction) tends to cause the wedge to be dragged further up theramp due to its frictional engagement with the surface of the endoscope.As the wedge is dragged further up the ramp, compressive force on theendoscope continues to increase to resist the distal removal force. Theeffect of dragging the wedge further into locking engagement duringapplication of a distal force is enhanced by the use of highlyfrictional materials in the components, such as hard rubber. Use ofstainless steel or other rigid materials may reduce the self-lockingeffect with the reverse ramp configuration.

In the case of a forward facing ramp configuration, the wedge alsoslides along the surface to provide a greater clearance distance betweenthe bracing member and wedge to permit installation of the device onto adistal end of an endoscope then permits sliding of the wedge to the highpoint of the ramp to reduce the clearance between the bracing member andwedge and creates compressive force on the endoscope and lock thedevice. Biasing members may also be used in the forward ramp embodiment.However, the wedge must be maintained at its distal most limit of travelalong the ramp at which point would occur the highest compressive forceon the endoscope. Because proximal movement of the wedge from this pointon the ramp would serve to reduce the compressive force on theendoscope, the forward ramp embodiment does not provide a self-lockingattribute of the ramp embodiment. Specifically, as a removal force isapplied to the accessory in the distal direction relative to theendoscope, the wedge, by its frictional engagement with the surface ofthe endoscope, would be dragged proximally, down the ramp, reducingcompressive loading on the endoscope. However, frictional engagement ofthe ramp against the surface of the endoscope is sufficient to provide alocked engagement capable of withstanding removal forces.

In another alternative embodiment of the invention, the attachmentmechanism may comprise a separate wedge element that is independentlyloadable onto the distal end of the endoscope and a ramp cone attachedto the accessory that is engageable over the cylindrical wedge. Thewedge may comprise an annulus having a cross-sectional shape of a wedge,having a flat inside surface that is parallel to the longitudinal axisof the endoscope and a sloped outside surface at an acute angle to thelongitudinal axis of the endoscope. As with the previous embodiments,the ramp surface created by the cone and the sloped surface of the wedgemay be oriented to be forward or reverse. However, as in the embodimentsdescribed above, the reverse ramp configuration provides a self-lockingfeature, when a pliable wedge material is used, such that a moving forceapplied to the accessory in a distal direction causes the ramp surfaceof the cone to push against the slope of the wedge causing compressionand increased engagement force on the surface of the endoscope.

It is an object of the present invention to provide an end oscopicaccessory attachment mechanism that can be easily and expeditiously usedto securely fasten an accessory to a distal end of an endoscope.

It is another object of the invention to provide an endoscopic accessoryattachment mechanism that increases locking force with the endoscope asa removal force acting to separate the accessory from the endoscope isapplied.

It is another object of the invention to provide an endoscopic accessoryattachment mechanism that utilizes the engagement between a ramp surfaceand a slope of a wedge to provide an adjustable engagement force with anendoscope that compresses the endoscope between the wedge and a bracingmember.

It is another object of the invention to provide an endoscopic accessoryattachment mechanism that accommodates a range of endoscope or cathetersizes.

It is another object of the invention to provide an endoscopic accessorycoupling, engageable with the distal end of an endoscope at one end andengageable with an accessory at its other end.

It is another object of the invention to provide a method of securing anendoscopic accessory to a distal end of an endoscope that requires aminimum of steps and results in secure engagement of the accessory.

It is another object of the invention to provide a method of securing anendoscopic accessory to a distal end of an endoscope that utilizes thecompressive force exerted on an endoscope by two surfaces of theaccessory for securement.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages of the invention will beappreciated more fully from the following further description thereof,with reference to the accompanying diagrammatic drawings wherein:

FIG. 1 is a side view of a preferred embodiment of the endoscopicaccessory attachment mechanism engaged with an endoscope;

FIG. 2 is an isometric view of a distal end of a typical endoscopehaving viewing capability;

FIG. 3 is a partial sectional side view of a prior art endoscopicsuturing accessory;

FIG. 3A is a detailed view of the suture tag shown in FIG. 3;

FIG. 4 is a partial sectional side view of a prior art endoscopicsuturing accessory;

FIG. 5 is a partial sectional side view of a prior art endoscopicsuturing accessory;

FIG. 6 is a top view of an endoscopic accessory comprising the rampsurface of the endoscopic attachment mechanism;

FIG. 7 is a side view of an endoscopic accessory comprising the rampsurface of the endoscopic attachment mechanism;

FIG. 8 is a side view of the wedge of the present invention;

FIG. 9 is a front view of the wedge of the present invention;

FIG. 10 is a bottom view of the wedge of the present invention;

FIG. 10A is an isometric view of the wedge of the present invention;

FIG. 11 is a side view of an endoscopic accessory comprising the rampsurface, wedge and bracing member with the wedge at the top of the rampsurface;

FIG. 12 is a side view of an endoscopic accessory comprising in a lockedposition;

FIGS. 13A-D present, in side view, a series of stages of the endoscopicaccessory comprising the attachment mechanism of the present inventionbeing loaded onto a distal end of an endoscope; and a side view of anendoscopic accessory being loaded onto a distal end of an endoscope FIG.14 is a diagrammatic illustration of a leverage tool being applied tothe attachment mechanism to provide manual sliding and locking of thewedge;

FIG. 15 is an isometric skeletal view of an alternate embodiment of thepresent invention utilizing a forward facing ramp surface;

FIG. 16A is a side view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a semicircular bracing member;

FIG. 16B is an end view of the alternate embodiment of the endoscopicaccessory attachment mechanism comprising a semicircular bracing member.

FIG. 17 is an alternate embodiment of the endoscopic accessoryattachment mechanism comprising a visor-like bracing member;

FIG. 18A is a side view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a short length circumferentialbracing member;

FIG. 18B is an end view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a short length circumferentialbracing member;

FIG. 19A is a side view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a long circumferential bracingmember;

FIG. 19B is an end view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a long circumferential bracingmember;

FIG. 20A is a side view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a funnel shaped ramp surfaceand a separable annular wedge;

FIG. 20B is an end view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a funnel shaped ramp surfaceand a separable annular wedge;

FIG. 21A is a side view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a funnel shaped ramp surfaceand a separable annular wedge;

FIG. 21B is an end view of an alternate embodiment of the endoscopicaccessory attachment mechanism comprising a funnel shaped ramp surfaceand a separable annular wedge;

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

The present invention provides an endoscopic accessory attachmentmechanism 2, which may be incorporated into an endoscopic accessory 4 toprovide secure attachment to the distal end of an endoscope 20, as isshown in FIG. 1. The principles of the attachment mechanism may beapplied equally well to catheter devices, though the invention isexplained in this description in the context of endoscopes. The primarycomponents of the mechanism are a ramp surface 60, a wedge 72 and abracing member 92 (shown in FIGS. 11-13). FIG. 2 shows the distal end 18of a flexible endoscope 20 with which the present invention may be used.Terminating at the distal face 16 of the endoscope are several channelsthrough which various functions may be performed. Typically, at leastone large working channel lumen 14 is provided through which variousmedical instruments, catheters or accessory control mechanisms may bepassed. In the case of viewing endoscopes, a viewing lens 12 is providedon the distal face of the endoscope to permit viewing via optical fiberor digital electronics that extend from the lens through the endoscopeto its proximal end and attach to viewing equipment external to thepatient. Lights 13 illuminate the treatment site so that it may beviewed through the lens 12. Some endoscopes also have a fluid port 15through which solution may be passed under pressure to rinse the lens ofbiological material during a procedure.

As mentioned above, the endoscopic accessory attachment of the presentinvention may be integrated with any type of endoscopic accessory.Examples of procedures that can be performed by accessory devicesattached to a distal end of an endoscope include band ligation,mucosectomy or endoscopic suturing for the treatment of such maladies asgastroesophageal reflux disease, among others.

To illustrate an example of an endoscopic accessory, FIGS. 3-5 depict aprior art endoscopic suturing device disclosed in U.S. Pat. No.5,792,153. FIG. 3 shows the distal end of a flexible endoscope 20, onwhich a sewing device 52 is attached. As mentioned above, the endoscopeis provided with a viewing channel, which is not shown, but whichterminates at a lens 12 on the distal face of the endoscope (FIG. 2).The endoscope is further provided with a biopsy channel 14, and asuction channel 24 the proximal end of which is connected to a source ofreduced pressure (not shown). The sewing device 52 has a tube 25, whichcommunicates with the suction pipe 24 and has a plurality ofperforations 26 therein. These perforations communicate with an upwardlyopen cavity 27 formed in the sewing device.

A hollow needle 28 is mounted in the biopsy channel 14, with its beveledtip extending into the sewing device. The needle has a channel 29extending therethrough. A flexible, wire-wound cable 30 has its forwardend attached to the rear of the needle 28, and a center wire 31 runswithin the cable 30, along the entire length thereof, and islongitudinally movable with respect thereto. The diameter of the wire 31is such that it is longitudinally movable within the channel 29 and, inthe position shown in FIG. 3, the distal end portion of the wire 31extends into the proximal end portion of the channel 29.

A thread carrier in the form of a tag 32 is mounted in the channel 29.The tag is shown in more detail in an enlarged view, shown in FIG. 3A.The tag may be hollow and has an aperture 33 extending through thesidewall thereof. As can also be seen in FIG. 3, one end of a thread 34is secured to the tag by passing it through the aperture 33 and tying inthe end of a knot 35 of sufficient size to prevent the thread escapingfrom the tag.

The sewing device accessory has a hollow head portion 36 defining achamber 40 therein, distal to the cavity 27. Between the chamber 40 andthe cavity 27 is a wall 37, in which there is formed an aperture 38. Theaperture 38 has a diameter that is marginally greater than the externaldiameter of the needle 28, and is aligned therewith. The clearancebetween the needle 28 and the aperture 38 must be sufficiently small toprevent tissue being forced through the aperture and causing the needleto jam. Finally, FIG. 3 shows a portion of the patient's tissue 39, inwhich a stitch is to be formed.

In operation, suction is applied to the suction pipe 24, and thus, tothe cavity 27 via communication through the perforations 26 in the tube25. The suction aspirates into the cavity a U-shaped portion 39 a of thetissue 39, as shown in FIG. 4. The hollow needle 28 is pushed throughthe U-shaped tissue portion 39 a by exerting a leftwards force on thewire-wound cable 30, and the tag 32 is pushed along the channel 29 fromright to left, by exerting a leftwards force on the center wire 31.After full advancement of the needle, the tip portion of the needle 28is on the left-hand side of the wall 37, within the chamber 40 in thehollow head portion 36, and the tag 32, within the channel 29, lies tothe left of the wall 37.

Continued leftwards movement of the wire 31 pushes the tag 32 out of thechannel 29 and into the chamber 40. The wire 31 is then withdrawnrightwardly, followed by rightward withdrawal of the cable 20, to bringboth back to the positions which they occupy in FIG. 3. The suction isthen discontinued so allowing the U-shaped tissue portion 39 a to bereleased from the cavity 27. The position of the components is then asshown in FIG. 5. Finally, the endoscope and sewing device are withdrawnfrom the patient. In so doing, the thread 34 is pulled partially throughthe tissue portion 39 a, since the tag 32 is trapped in the chamber 40.The end result is that both ends of the thread are outside of thepatient and can be knotted and/or severed as may be appropriate. Itshould be noted that a multiple stitch embodiment also is disclosed inU.S. Pat. No. 5,792,153.

FIG. 6 shows a top view of an endoscopic accessory comprising a suturecapsule body 352 similar to the prior art device described above, butemploying an attachment mechanism of the present invention. FIG. 7 showsa side view of the endoscopic suture capsule 352. The suture capsule maybe machined and assembled from a rigid material such as stainless steelor a polymer and comprises a proximal end 354 and a distal end 356. Thedistal end of the capsule body may include threads 358 to threadablyreceive a cap (not shown), similar to cap 36 described above. Thecapsule also comprises a cavity 327 into which is sucked a portion oftissue to be sutured as is described above. At the proximal end of thecapsule body is formed, the attachment mechanism 302, which serves tosecure the capsule to the distal end of an endoscope. FIGS. 6 and 7 showone component of the attachment mechanism: a ramp surface 360. The rampsurface lies in a plane, which is at an acute angle 364 to thelongitudinal axis 362 of the endoscopic accessory 304. In the example ofthe suturing capsule body 352, the capsule is intended to be mounted tothe distal end of the endoscope such that its longitudinal axis 362 isparallel to the longitudinal axis of the endoscope. Immediately proximalto the ramp surface 360 is a backstop 368 against which rests the distalface 16 of an endoscope when fully engaged with the accessory 304.However, flush engagement with the backstop may not be necessary toachieve adequate engagement.

The ramp surface 360 has one or more keyways 370 to receive projections374 of a wedge 372 which is slidable on the ramp surface to transmitcompressive force to a surface of an endoscope such as the outsidesurface 11 (FIG. 2). FIG. 8 shows a side view of the wedge 372. FIG. 9is a front view of the wedge, FIG. 10 is a bottom view and FIG. 10A isan isometric view of the bottom of the wedge. The wedge normally residesatop the ramp surface 360 of the attachment mechanism 302, but is shownseparately in these figures to illustrate the features of thiscomponent.

The wedge comprises a top surface 376, which is parallel to thelongitudinal axis 380 of the wedge. The wedge also includes a bottomsurface 378, which is oriented at an acute angle 364 to the longitudinalaxis 380 of the wedge. When the bottom surface 378 is in matingengagement with the ramp surface 360, both inclined at an acute angle θ364, the top surface 376 of the wedge remains parallel to thelongitudinal axis of the endoscope and thus the outside surface of theendoscope 11. The top surface 376 has a curved shape to match the arc ofthe outside surface 11 of the endoscope as is best seen in FIG. 9. Soshaped, the top surface 376 acts as an engagement pad for contacting theendoscope surface and applying compressive force without damaging thesurface of the endoscope. Alternatively, the wedge may have a topsurface that is rounded so that only an arc shaped line contacts theendoscope.

Spring guide holes 373 are formed into the front face 382 of the wedgeto hold and restrain biasing members such as small coil springs 348.Additionally, the wedge includes engagement ridges 384 etched into theside surfaces 386 of the wedge. The engagement ridges are arranged tocoincide with projections on an optional, separate loading tool topermit the operator to apply a longitudinal force to the wedge only toadjust force applied to the endoscope surface. In the endoscopicsuturing capsule, body 352, a suction tube 25 is required to provide avacuum source to the cavity 27. Because this suction tube 25 extendsthrough the ramp surface area, the bottom surface 378 of the wedge 372has a crescent shape contour 375 cut-out to provide clearance for thesuction tube 25. However, such a crescent contour 375 would not berequired in embodiments where a suction tube was not used. Additionally,projections 374 protrude from the bottom surface 378 of the wedge toride in keyways 370 formed into the ramp surface. The projections andkeyways help to maintain the wedge aligned as it slides on the ramp orup and down the ramp surface 360. The projections may be fitted intoprojection receptacles 390 formed into the bottom surface of the wedge.

FIGS. 11 and 12 show side views of the endoscopic accessory 304,specifically a suturing capsule body 352 comprising all components ofthe attachment mechanism in their operational relationships. A bracingmember 392 extends proximally from the capsule body 352 to engage asurface of the endoscope. The bracing member has a longitudinal axis 394that is parallel to the longitudinal axis of the endoscope 10 andlongitudinal axis of the capsule 362 and wedge 380. In the example shownin FIG. 11, the bracing member 392 comprises a tube that is receivablewithin a portion of the working channel 14 of an endoscope. The bracingmember, in this instance, has a lumen 396 to permit passage ofinstruments or controls through the working channel of the endoscopeinto the endoscopic accessory 304, such as the needle 28 and suture tag32 of the endoscopic suturing device discussed in detail above.

As the wedge 372 slides up the ramp surface 360 from a loading positionto a locked position at the top of the ramp surface 360, as shown inFIG. 12, the distance D 398 between the top surface 376 of the wedge andthe bottom surface 402 of the bracing member decreases to capture andapply a compressive force to a portion of an endoscope capturedtherebetween. In a first position wherein the wedge is located at thebottom of the ramp surface as is shown in FIG. 11, a distance D 398exists between the bottom surface 402 of the bracing member and the topsurface 376 of the wedge 372. In this position, there is sufficientclearance for a portion of a distal end of an endoscope to slidetherebetween so that the accessory 304 can be mounted to its distal end.In a second position wherein the wedge 372 is positioned at the top ofthe ramp surface 360, as shown in FIG. 12, a reduced distance d 400exists between the bottom surface 402 of the bracing member and the topsurface 376 of the wedge. In this position, the surfaces 402 and 376engage working channel surface 17 and outer surface 11, of theendoscope, tightly capturing the endoscope and locking the accessory 304to its distal end

FIGS. 13A-13D show progressive steps of loading an endoscopic accessory304 onto a distal end 18 of an endoscope 20 using the attachmentmechanism 302 of the present invention. In FIG. 13A, the bracing member392 is inserted into the working channel 14 at the distal end 18 of anendoscope 20. Initially, biasing members, such as small coil springs 348maintain the wedge 372 at the top of the ramp surface 360. In FIG. 13B,the accessory 304 is moved more proximally with respect to the distalend of the endoscope. The bracing member 392 continues to travel furtherinside the working channel 14 of the endoscope and the distal face ofthe endoscope 16 begins to contact the wedge member 372. A slightbeveled edge 406 at the proximal end 408 of wedge 372 may be provided tohelp guide the distal end of the endoscope onto the top surface 376 ofthe wedge. Because of the floating arrangement of the wedge 372 on rampsurface 60, the wedge may be adjusted and rotated slightly around thepeak 410 of ramp surface 360 to additionally facilitate loading of thedistal end of the endoscope onto top surface 376. As shown in FIG. 13C,as the accessory is pushed proximally relative to the distal end of theendoscope, the wedge 372 is pushed distally to travel down the ramp 360,thereby increasing the distance between the top surface of the wedge 376and the bottom surface of the bracing member 392 to provide adequateclearance to accept the endoscope therebetween. Springs 348 becomecompressed as the wedge slides down the ramp 360 and increasing amountsof potential energy is stored in them to force the wedge 372 backproximally up the ramp to maintain a contact fit between the endoscopesurface 11 and top surface 376 of the wedge.

FIG. 13D shows the accessory 304 and endoscope 20 after loading has beencompleted. The distal face 16 of the endoscope abuts the backstop 368 ofthe accessory 4, bracing member 392 is fully inserted into workingchannel 14 and bottom surface 402 of bracing member 392 engages lumensurface 17 of the working channel. The presence of the bracing memberwithin working channel 14 and the engagement of the surfaces presents acompressive force created by upper top surface 376 of wedge 372,resiliently pushed into engagement with endoscope surface 11 by springs348, which bias the wedge up the ramp 360. In this position, sufficientfrictional contact between surfaces of the attachment mechanism 302 andsurfaces of the endoscope 20 exist to hold the accessory 304 in place atthe distal end 18 of the endoscope. It is important to note that thedistal face 16 of the endoscope need not necessarily abut the backstop368 to be considered securely loaded onto the endoscope. The position ofthe wedge along the ramp surface at the point secure engagement isachieved may vary depending on the diameter of the scope or catheter inquestion. In this sense, the ramp arrangement provides a securementmechanism that can accommodate a variety of scope sizes.

FIG. 14 demonstrates the use of a loading tool 420 in securing the wedgeinto firm engagement with the outer surface 11 of the endoscope. TheY-shaped tool 420 comprises a handle 422 (at the base of the Y shape).Two forks 424, which surround the attachment mechanism 302 between theforks 424, U-shaped recess 426 is defined having an engagement ridge 428that interlocks with the engagement groove 384 defined on the sidesurface 386 of the wedge 372. After the accessory 304 has been advancedproximally as far as possible relative to the endoscope during mounting,the user can position the tool such that engagement ridge 428 interlockswith engagement groove 384. The user then can apply a longitudinal forceon the wedge 372 in a proximal direction through the tool 420 to insurethat the wedge has been displaced as far as possible up the ramp toapply a secure compressive force against the outside surface 11 of theendoscope.

FIG. 15 shows an alternate embodiment 502 of the attachment mechanismhaving a forward facing ramp 560. The ramp surface 560 is forward facingin the sense that the acute angle that the ramp forms with thelongitudinal axis of the endoscope 10 defines a rise R (as shown in FIG.7) that increases in the proximal direction (the opposite direction fromthe reverse ramp embodiment described above). In use, after theaccessory body 504 is loaded onto the distal end 18 of the endoscope 20,the wedge 572 is affirmatively slid up the ramp 560 (in a distaldirection) to bring the top surface 576 of the wedge into firm contactwith the outside surface 11 of the endoscope. The compressive forcecreated by the top surface of the wedge is opposed by the bracing member592 residing in working channel 14, in contact with working channellumen surface 17.

As shown in FIGS. 16-21B, the bracing member need not be inserted intothe working channel of the endoscope to engage the inside surface 17 ofthe working channel lumen in order to brace the force provided by thewedge 772 on the outside surface of the endoscope. Alternate embodimentsof the attachment mechanism have a bracing member configured to engage aportion of the outside surface of the endoscope 11 as well as, but in anorientation that opposes the force provided by the wedge 772. FIG. 16Ais a side view of an alternate embodiment of the attachment mechanismcomprising such a bracing member and accessory 704. The attachmentmechanism 830 comprises the same arrangement of ramp surface 760 andwedge 772 as in the previous embodiments but substitutes a bracingmember 838 that comprises a C-shaped band 834. As shown in FIG. 16A andthe corresponding end view as shown in FIG. 16B, the C-shaped bandcurves around the bottom 836 of the attachment mechanism 830 and theends 838 of the C-shaped band extend more than halfway around each sideof the circumference of the endoscope to provide an opposing force 840against the surface 11 of the endoscope in opposition to the upwardforce 842 resulting from engagement of the top surface 776 of wedge 772.The C-shaped band must necessarily be formed from a rigid polymer orstainless steel to provide the requisite rigidity to resist bending atthe ends 838 as a result of the engagement force provided by the wedge772.

FIG. 17 shows a side view of another alternate embodiment of theattachment mechanism 848. Like the alternate embodiment of FIGS. 16A and16B, the bracing member engages the outside surface 11 of the endoscopeto provide an opposing force to that generated by the wedge 772 as it ismoved up the ramp surface 760. However, the engagement mechanism 848realizes a bracing member 846 that extends proximally from theendoscopic accessory to engage the top 850 of the endoscope over arelatively narrow arc of its circumference, just sufficient to preventthe endoscope from slipping out of contact with the bracing member 846.The bracing member in this embodiment may have a visor shape to capturea sufficient arc length of the circumference of the top of the endoscope850. The curved shape of the top surface 776 of the wedge 772 likewiseprovides engagement with an adequate arc length of the endoscope surfaceto prevent inadvertent disengagement from the attachment mechanism 848.

FIG. 18A shows a side view of another alternate embodiment of thepresent invention wherein the bracing member 864 engages the outsidesurface of the endoscope 20. The attachment mechanism 860 comprises abracing member 864 configured as a short length circumferential bandthat encircles the bottom of the engagement mechanism 868 and continuesaround the endoscope to encircle the top 850 of the endoscope as well.

FIGS. 19A and 19B show an attachment mechanism 870 that is similar inconfiguration to that described in connection with FIGS. 18A and 18B.However, the circumferential band is of a longer length to contactgreater surface area of the endoscope 20. The bracing member 874comprises a cylindrical band, which encircles the ramp surface 760 andwedge 772 components of the mechanism and provides an opposing force atthe top of the endoscope 850 to lock the accessory 704 onto the distalend of the endoscope. The embodiments of FIGS. 16A-19B may use biasingmembers fabricated from hard rubber, nylon or stainless steel and may beattached to attachment mechanism by adhesive, rivets or other suitablemeans.

FIGS. 20A and 20B show another alternate embodiment of the attachmentmechanism 880 comprising a separate wedge element 882 that isindependently loadable onto the distal end 18 of the endoscope and acircumferential ramp cone 884 attached to the accessory 704 that isengageable over the cylindrical wedge 882. The wedge may comprise anannulus having a cross-sectional shape of a wedge: a flat inside surface886 that is parallel to the longitudinal axis 10 of the endoscope and asloped outside surface 888 at an acute angle to the longitudinal axis ofthe endoscope. As with the previous embodiments, the ramp surfacecreated by the cone 884 and the slope surface of the wedge may beoriented to be forward or reverse. However, FIGS. 21A and 21B show acone and annular wedge embodiment 890 oriented in the reverse direction,such that rise defined by the acute angle created between thelongitudinal axis 10 of the endoscope and the axis 898 of the cone rampsurface 894 increases in the distal direction. As in the preferredembodiment described above, the reverse configuration can help toprovide a self-locking feature, when a pliable wedge material is used.In this instance a longitudinal force applied to move the accessory in adistal direction causes the ramp surface of the cone to push against theslope of the wedge causing compression and increased engagement force onthe surface 11 of the endoscope.

Additionally, the embodiments of FIGS. 20A-21B demonstrate analternative configuration for engaging an accessory device.Specifically, the distal end 900 of the cone in each embodimentcomprises a straight portion 902 that may be configured with a universalfitting connectable to a wide range of endoscopic accessories. Forexample the straight portion of the cone may have internal threads onits inside surface 904 to threadably receive a line of endoscopicaccessories having external threads of the same size. Alternatively, theaccessory may be joined to the opening defined at the distal end of thecone 900 by a snap fit, friction fit or adhesive. In this manner, theattachment mechanism serves as a universal connector or coupling betweenan endoscope and accessory.

Preferred materials for the embodiments of FIGS. 20A-21B include hardrubber to increase the coefficient of friction between the annular wedgeand the cone. However at least the straight portion 902 of the coneshould be formed from a more rigid material such as stainless steel or ahard polymer to provide a surface into which threads may be formed.

It should be understood however, that the foregoing description of theinvention is intended merely to be illustrative thereof and that othermodifications, embodiments and equivalents may be apparent to those whoare skilled in the art without departing from its spirit.

1. An endoscopic accessory attachment comprising: proximal and distalends, a bracing member having a longitudinal axis engageable with atleast one surface of an endoscope, a ramp surface that is at an acuteangle to the longitudinal axis of the bracing member, a wedge slidableon the ramp surface to provide variable engagement force on a surface ofthe endoscope in opposition to that provided by the bracing member. 2.An endoscopic accessory attachment as defined in claim 1 wherein theangle of the ramp surface defines a rise relative to the longitudinalaxis of the bracing member that increases in the distal direction.
 3. Anendoscopic accessory attachment as defined in claim 2 wherein theengagement force on the surface of the endoscope increases as alongitudinal force is applied to move the accessory longitudinally in adistal direction, relative to the endoscope.
 4. An endoscopic accessoryattachment as defined in claim 1 wherein the angle of the ramp surfacedefines a rise relative to the longitudinal axis of the bracing memberthat increases in the proximal direction.
 5. An endoscopic accessoryattachment as defined in claim 4 wherein the engagement force on asurface of the endoscope increases as a force is applied to move theaccessory in a longitudinal direction relative to the endoscope in aproximal direction.
 6. An endoscopic accessory attachment as defined inclaim 1 further comprising a top surface and an inclined bottom surfaceon the wedge angled to correspond with the ramp surface of the accessoryand oriented in the opposite direction from the ramp surface such thatthe bottom surface and ramp surface are in mating contact such that thetop surface of the wedge is substantially parallel to the longitudinalaxis of the bracing member.
 7. An endoscopic accessory attachment asdefined in claim 1 wherein the bracing member is configured to engagethe surface of a working channel of the endoscope.
 8. An endoscopicaccessory attachment as defined in claim 1 wherein the bracing membercomprises a surface configured to engage at least a portion of anoutside surface of the distal end of the endoscope.
 9. An endoscopicaccessory attachment as defined in claim 8 wherein the bracing membersurface is a cylindrical member that engages the entire circumference ofthe distal end of the endoscope.
 10. An endoscopic accessory attachmentas defined in claim 8 wherein the bracing member surface is inclined atan acute angle to the longitudinal axis of the endoscope.
 11. Anendoscopic accessory attachment as defined in claim 9 wherein the wedgecomprises an annulus, separable from the accessory.
 12. An endoscopicaccessory attachment as defined in claim 1 further comprising a biasingmember to bias the wedge toward the proximal end of the ramp.
 13. Anendoscopic accessory attachment as defined in claim 1 further comprisingmeans positioned on the wedge for engaging with a separate leverage toolconfigured to permit the user to slide the wedge along the ramp surface.14. An endoscopic accessory comprising: a self-locking attachmentmechanism that is configured to increase engagement force on anendoscope as a longitudinal force is applied to move the accessorylongitudinally and relative to the endoscope.
 15. An endoscopicaccessory as defined in claim 14 wherein the mechanism is configured toincrease engagement force when a longitudinal force is applied to theaccessory in a distal direction.
 16. An endoscopic accessory as definedin claim 14 wherein the engagement force increases as the longitudinalforce is applied to the accessory in a proximal direction.
 17. A methodof securing an endoscopic accessory to a distal end of an endoscopecomprising: providing an endoscope; providing an accessory having atleast a first surface and a second surface at an acute angle to thefirst surface; placing the accessory in engagement with an endoscopesuch that the first surface of the accessory engages the surface of anendoscope in the parallel relationship and the second surface of theaccessory places an increasing engagement force on a surface of theendoscope as a force is applied to move the accessory longitudinallyrelative to the endoscope.
 18. A method of securing an endoscopicaccessory as defined in claim 17 further comprising: providing a wedgeand sliding the wedge relative to the second surface of the accessory toengage and apply engagement force on a surface of an endoscope whichopposes a resisting force applied by the first surface of the accessory.19. An endoscopic accessory attachment mechanism comprising: a wedgeengageable with an outside surface of an endoscope, a cone, sized to fitclosely over the surface of the wedge when it is engaged with theendoscope.
 20. An endoscopic accessory attachment coupling comprising:proximal and distal ends, means for attaching to a distal end of anendoscope at the proximal end, and means for attaching to an endoscopicaccessory at the distal end.